Boiler



R. E. ZOLLER Feb. 4, 1947.

BOILER Filed Sept 1, 1942 #VVA-Wrog /g0ha/d EZo/ler Patented Feb. 4, 1947 BOILER Ronald Ernest Zoller, London, England, assignor to The Babcock & Wilcox Company, Newark, N. J., a corporation of New Jersey Application September 1, 1942, Serial No. 456,857

In Great Britain September 2, 1941 Claims.

This invention relates to tubulous boilers and particularly to boilers, hereinafter called double flow boilers, in which the gases of combustion flow from a, combustion chamber or chambers through gas flow paths on opposit sides of a vapour and liquid drum or adjacent vapour and liquid drums. The invention is concerned with such boilers which are liable to operate with distribution of the total gas flow in varying proportions between the gas flow paths, an object being to provide an economizer arrangement which comprises parts respectively included in the gas flow paths on opposite sides of the vapour and liquid drum or drums of an associated boiler so that little if any additional head room is required for the accommodation of the economizer above the boiler and which operates efl'iciently Whatever the distribution of gases in the two paths. A further object is to avoid at least largely the danger of vapourization occurring in the part of the economizer included in one of the gas flow paths in the event. of the gas flow in that path being greatly increased at the expense of the gas flow in the other path.

A double flow boiler, liable to operate with distribution of the total gas flow in varying proportions between the gas flow paths, according to the present invention comprises an economizer including two parallel liquid flow paths each of which is disposed partly in one of the gas flow paths of the boiler and partly in the other gas flow path of the boiler.

Th invention will now be described, by way of example, with reference to the accompanying drawing in which:

Figure 1 is a partly diagrammatic sectional front elevation of a three drum boiler suitable for marine work; and

Figure 2 is a diagram showing two economizer sections in a gas flow path.

The boiler illustrated by Figure 1 includes an upper steam and water drum I and two lower drums 2 and 3, respectively connected with the upper drum by banks 4 and 5 of inclined tubes. Some of the tubes of the tube bank 4 form a screen 6 for a superheater '5 disposed in a space between the said tubes and the remaining tubes of the tube bank.

Below the tube banks 4 and 5 is a furnace chamber 8 arranged to be fired by burners fitted to the parts 9 in the front wall of the chamber. There are two separate paths for the flow of gases from the furnace chamber 8 to a common flue 21, one path being through the tube screen 6, superheaterl and the remainder of the tubes of the bank 6 and through a gas passage lfl o-n one side of the upper drum l to the common flue; the other path being through the tube bank 5 and gas passage H to the common flue. The passages H3 and H are so arranged that a free space 23 remains above the upper drum I.

In the gas passage Ill are disposed economizer sections I4 and H5 and in the gas passage II are disposed other economizer sections l 6 and H, the

lower parts of the sections l5 and I! being substantially on a level with the centre line of the upper drum l. At their outlets the gas passages are provided with dampers l2 and 13 respectively for enabling the distribution of the total gas flow between the passages l6 and II to be controlled and the degree of superheat thereby to be regulated.

Th economizer, as indicated by Figure 2, is suitably of bent tube form, each section including amultiplicity of sinuous tub-es connected between a pair of headers 26.

A pipe It for the passage of feed Water to the economizer supplies the branch pipes l9 and 20 leading to the upper headers of the economizer sections I l and i5 respectively. The lower header of the section I4 is connected by th pipe 2! with the lower header of the'economizer section H; the lower header of section I5 is connected by the pipe 22 with the lower header of the section 15; and the upper headers of the sections 11 and I5 are respectively connected by pipes 23 and 2'3 with a common pipe 25 leading to the upper drum I. It follows, therefore, that the economizer sections M and I6 operate in counterflow whilst the sections IEand I! operate in parallel-flow with respect to the gases. It follows also that there are two paths in parallel for the feed water, one path being first through the counterflow section It in the gas passage It and then through the parallel-flow section H in the gas passage H; the other path being first through the counter-flow section 56 in the gas passage H and then through thepara'llel-flow section iii in the gas passage l5]. Separate valves, not shown, are provided for the control ,oithe flow of water through the respective parallel flow paths, whilst a further valve is included in the pipe is.

The economizer sections I4 and it are similar to one another and are larger than the sections l5 and I? which are also similar to one another and if the water is to be heated in the economizer close to the temperature of evaporation, the.

counterflow sections l4 and it which are further from the furnace chamber B than the parallelflow sections [5 and II, are preferably sufficiently larger than the parallel-flow sections to ensure that, when substantially all of the gases are diverted to one of the gas passages, the water is substantially equally heated in the two parallel feed Water paths. Thus, if the gases ar wholly diverted to the gas passage II, the heating surfaces of the economizer sections l6 and ii are suitably in inverse ratio to the differences in the mean gas temperatures for these sections when the gases are so diverted.

The economizer sections l4 and It may be considered as primary sections inasmuch as the water first flow through these sections from a common source after leaving the inlet pipe IS. The economizer sections l5 and ll may similarly be considered as secondary economizer sections inasmuch as each of them receives water from one of the primary economizer sections.

In the arrangement described, since the economizer is disposed below the junction of the two gas flow paths from the furnace chamber, little if any additional head room is required for the accommodation of the economizer. All of the gases are subject to cooling by water of the lowest temperature and the whole of the Water passing through the economizer is heated, however the gas flow is distributed between the passages I and H. Moreover, should the whole of the gases be caused to flow through one of the passages, both sections of economizer in that passage are fed with cold Water.

In the normal, or average operation of the installation indicated in Fig. 1, it is intended that if any vaporization does occur it will take place in a parallel-fiow section of the economizer, where the water flow is in a generally upward direction, so that the ill efiects of Vapourization are minimised. I

When vapourization in the economizer is unlikely to occur whatever the division of the gas flow between the two passages, the whole of the economizer may advantageously be arranged in counter-flow with respect to the gases.

The necessary modifications for applying the invention to other forms of double flow boiler will be clear without further description to those skilled in the art. The varied distribution of the total gas flow may be produced in any suitable manner.

What is claimed is:

1. In a steam boiler having two heating gas passes in parallel, steam generating tubes over which furnace gases flow to said passes, 'a superheater connected to the steam generating tubes and heated mainly'by the gases flowing to one of said passes, gas flow regulator means causing unequal flow of gases in said gas passes. and an economizer presenting two parallel water flow paths leading toward the steam generating tubes, each of said paths having a primary part consisting of a bank of series connected tubes disposed in one of said passes and a secondary part consisting of a bank of series connected tubes disposed Wholly in the other pass, each primary economizer part being counter-flow and disposed on the downstream (gas) side of a parallel flow secondary economizer part.

2. In a steam generator, means forming a plurality of heating gas passes in parallel arrange ment, tubes forming heat convection absorbing surfaces normally unequally effective upon the gases for said passes, damper means adapted to cause unequal gas flow in said passes, and auxiliary fluid heating means in said passes presenting a plurality of separate fluid flow paths with each path disposed partly in one pass and partly in another, said auxiliary means being subject to the gases after the latter have passed over said tubes, said auxiliary means consisting of primary and secondary spaced banks of tubes in each gas pass and connections between the outlet of each primary bank and the inlet of the secondary bank of tubes in the other gas pass so that the fluid confined to either of the primary banks flows therefrom to the secondary bank of tubes in the other gas pass.

3. In a steam boiler having two heating gas passes arranged in parallel, flow regulator means adapted to cause unequal gas flow in said passes, tubes presenting steam generating surfaces over which furnace gase flow through said passes, a superheater connected to the steam generating tubes and heated mainly upon the gases entering one of said passes, and auxiliary fluid heating means presenting two separate liquid flow paths each of which has a primary part disposed in one of said passes and a secondary part disposed in the other pass, said auxiliary means consisting of primaryand secondary spaced banks of tubes in each gas pass and connections between the outlet of each primary bank and the inlet of the secondary bank of tubes in the other gas pass so that the fluid confined to either of the primary banks flows therefrom to the secondary bank of tubes in the other gas pass.

4. In fluid heat exchange apparatus, means forming a plurality of heat exchange gas passes arranged in parallel, spaced tubes forming convection heat-exchange surfaces contacted by the gases for said passes, fio-w regulator means adapted to cause unequal gas flow in said gas passes, and auxiliary fluid heat exchange means.

in said passes presenting a plurality of fluid'fiow paths arranged in parallel with each path disposed partly in one pass and partly in another, said auxiliary means being subject to the gases after the latter have passed over said tubes, said auxiliary means consisting of primary and secondary spaced banks of tubes in each gas pass and connections between the outlet of each primary bank andthe inlet of the secondary bank of tubes in the other a gas pass so that the fluid confined to either of the.

primary banks flows therefrom to the secondary bank of tubes in the other gas pass.

5.- In a steam generator, steamv generating tubes, fuel burning means for supplying furnace ases to heat the tubes, means providing two.

separate heating gas passes, flowregulator means causing unequal gas flow in said passes, a superheater screened by some of the said tubesand being heated mainly by gases passing from said fuel burning means to one of said passes, means connecting the superheater with the steam gen-.

erating tubes,a primary counter-flow economiaer section in each of said passes, a secondary par-; allel flow economizer section in each of said passes and'disposed between a primary section and the fuel burning means, and cross-over economizer connections eachleading from the outlet of a primary economizer section in one pass'to the RONALD ERNEST ZOLLER.

Number REFERENCES CITED 1,969,405 The following references are of record in the 500,803 file of this patent: 5 5 332: UNITED STATES PATENTS 2:013:985

Number Name 1 Date 2,232,935 Bailey Feb. 25, 1941 2,092,299 Black et a1 Sept. 7, 1937 Number 2,243,913 Marshall June 3,1941 10 21,8 3 2,247,884 Kerr et a1 July 1, 1941 6 Name Date Kerr Aug. 7, 1934 Finlayson et a1. July 4, 1893 Seabur July 24, 1894 Schmidt Ja.n. 18, 1916 Kerr Sept. 10, 1835 FOREIGN PATENTS Country Date British 1909 British 1912 

